A growing method to defeat electronic article surveillance (“EAS”) systems is the use of readily available metal foils such as aluminum foil to shield EAS markers from detection by an EAS system. Thieves often line the insides of shopping bags, handbags and backpacks with metal foil to provide a concealed compartment for placing items to be stolen while inside the store so that they can exit through the detection zone of an EAS exit systems without detection. In response to this problem, retailers are increasingly using metal detection systems tuned to detect metal foil so that they can be alerted if a foil lined bag or backpack passes through the exit.
A major problem with this approach is that there are many metal objects and products that pass through the EAS system detection zone that are not related to theft. Some examples of these items are shopping carts, wheel chairs, products that have metal or aluminized packaging, and foil bags used for keeping hot serve deli items warm, etc. The effectiveness of a metal detection system is dependent on reducing alarms from non-theft items that pass through the detection zone and increasing detection of actual foil lined bags and backpacks.
Metal detectors are typically formed with a transmitter and receiver pair. The transmitter transmits a signal and the receiver receives the transmitter signal which is attenuated and/or shifted in phase when metal is inside the interrogation zone. Traditionally, these systems discriminate between foil lined bags and other metal objects by only alarming when detecting metals that have a responsive signal with amplitudes that fall in a range that is indicative of foil lined bags rather than other items. Unfortunately, relying on amplitude is not entirely reliable because a foil lined bag that is physically close to a metal detector antenna may exhibit a responsive signal strength similar to that of a shopping cart that is located further away from the metal detector. This problem forces the metal detection systems to be confined to narrow openings and to narrowly limit the range for positive detection of foil lined bags which causes the sensitivity of the system to be degraded.
As another attempted solution, retailers sometimes place metal detection systems so that shopping carts cannot pass. In other words, the metal detectors and/or EAS systems are arranged such that shopping carts will not fit through the exits. However, controlling the flow of traffic to eliminate false alarms from shopping carts interferes with the normal behavior of customers and degrades the customer experience. Since a positive customer experience is extremely important to retailers, this approach is usually undesirable.
Retailers may also eliminate products that cause false alarms, such as metallic or metalized packaging, or foil lined bags for keeping hot serve deli items warm, etc. Eliminating products that cause false alarms also degrades the shopping experience and limits the customer choices that are extremely important to retailers. Thus, this approach is also undesirable to retailers.
Therefore, what is needed is a system and method that can identify items that are likely to be used as foil lined containers so that metal detector signals can be confirmed, as well as automatically identifying items entering a detection zone that could cause false alarms and inhibiting these false alarms.